JP4439983B2 - Control device - Google Patents

Description

  The present invention relates to a control device for a runaway caused by a failure of a logic circuit component or the like in a device such as a microcomputer that controls a microwave oven or an electric oven.

  Conventionally, in this type of control device, even if a microcomputer that controls energization of a microwave oven or a heater runs away, heating does not start unless an operator presses a start switch (see, for example, Patent Document 1). .

FIG. 3 shows a conventional control device described in Patent Document 1. In FIG. As shown in FIG. 3, the latch circuit 26, the start switch SWS (16), the output terminal A of the microcomputer that supplies power for the latch circuit, the relay coil RyA, the relay coil, and the latch circuit The transistor Q3 is connected to the output terminal.
JP-A-60-132202

  However, in the conventional configuration, if the clock circuit attached to the microcomputer breaks down during the heating operation by the microwave oven or the heater, the microwave oven or the heater continues the closed state of the relay contact for controlling energization, There was a problem that the heated object continued to be heated abnormally. In particular, in a microwave oven, if the control circuit fails during heating and continues to heat, the object to be heated such as food is dried and carbonized, and a spark is generated on the surface of the carbide by the radio wave of the microwave and the object is heated. Fire accidents such as igniting objects are likely to occur.

  The present invention solves the above-mentioned conventional problems. Even when the microcomputer runs away, heating is not started unless the operator presses the start switch, and the clock circuit attached to the microcomputer is in the middle of heating. It is an object of the present invention to provide a control device that stops heating an object to be heated when there is a failure.

In order to solve the conventional problems, a control device of the present invention includes an operation unit, a microcomputer, a latch circuit, a relay that opens and closes power to a load, and the relay and an output terminal of the latch circuit. A first transistor connected in between, a pulse smoothing circuit connected to the latch circuit, and a second transistor connected between the pulse smoothing circuit and the latch circuit and supplying power to the latch circuit The operation unit has an operation start switch for instructing operation start, and the microcomputer has a first output terminal for supplying a pulse voltage of a rectangular wave to the pulse smoothing circuit, and a first transistor A second output terminal for controlling conduction; the latch circuit includes third and fourth transistors; and the fourth transistor includes the operation start switch. There are connected, the the third transistor is supplied with power via said second transistor, said the second transistor of the pulse smoothing circuit
The control device is configured to be connected to an output terminal .

  Thereby, in a conventional logic circuit such as a microwave controlled by a microcomputer, for example, since a relay is generally driven by an output terminal of the microcomputer, an abnormality in which heating is started by a runaway of only the microcomputer, Alternatively, the control circuit according to the present invention can solve the problem of the conventional patent, which is that the microcomputer clock circuit breaks down and the operation continues, and the object to be heated continues abnormally. It can be avoided. That is, when the operation of the microcomputer is stopped due to a failure in the clock circuit of the microcomputer in FIG. 1, the pulse waveform that should be originally generated is present at the first output terminal that supplies the rectangular pulse voltage. No longer occurs. Then, the pulse smoothing circuit connected thereto loses the input pulse, thereby losing the drive signal of the second transistor in the subsequent stage generated by smoothing the pulse waveform, and the collector and emitter of the second transistor. The supply of power that was supplied to the latch circuit via the second transistor is stopped due to the disconnection between the two, and therefore the heating of the microwave oven is stopped by opening the contact of the relay that opens and closes the energization to the heating device. Then, the problem that the heated object keeps heating abnormally is avoided.

The microcomputer further includes a first output terminal that supplies a pulse voltage of a rectangular wave to the pulse smoothing circuit, a second output terminal that controls conduction of the first transistor, and a third output terminal connected to the operation start switch. The latch circuit has third and fourth transistors, the operation start switch is connected to the fourth transistor, and the third transistor is connected to the second transistor via the second transistor. Power is supplied, and the output terminal of the pulse smoothing circuit is connected to the second transistor .

As a result, a pulse waveform is generated at the second output terminal when the operation switch is operated, power is supplied to the latch circuit before the operation start switch is pressed, and the fourth transistor is turned on when the operation start switch is pressed. The operation is started until the power is supplied to the latch circuit by conducting the first transistor by the signal from the second output terminal at almost the same time and operating the relay that opens and closes the power to the load. The problem that the switch must be kept pressed can be solved .

  The control device of the present invention solves the above-described conventional problem. Even when the microcomputer runs away, the microcomputer does not automatically start heating unless the operator presses the start switch. Even if there is a failure such as the clock circuit attached to the controller being stopped, it is possible to provide a control device that can be safely stopped without continuing to heat the object to be heated.

In the first invention, a relay that opens and closes power to a load is connected in series with a first transistor controlled by a microcomputer and a latch circuit that operates in response to a signal from an operation unit having an operation start switch. The power for driving the latch circuit is supplied only when the signals of the first and second signals are overlapped, and the power supply for driving the latch circuit has the second transistor only when the pulse signal from the microcomputer is supplied to the pulse smoothing circuit. controlled and is obtained by the control equipment that the supply power to the latch circuit.

  Thereby, in a conventional logic circuit such as a microwave controlled by a microcomputer, for example, since a relay is generally driven by an output terminal of the microcomputer, an abnormality in which heating is started by a runaway of only the microcomputer, Alternatively, the control circuit according to the present invention can solve the problem of the conventional patent, which is that the microcomputer clock circuit breaks down and the operation continues, and the object to be heated continues abnormally. It can be avoided. That is, when the operation of the microcomputer is stopped due to a failure in the clock circuit of the microcomputer in FIG. 1, the pulse waveform that should be originally generated is present at the first output terminal that supplies the rectangular pulse voltage. No longer occurs. Then, the pulse smoothing circuit connected thereto loses the input pulse, thereby losing the drive signal of the second transistor in the subsequent stage generated by smoothing the pulse waveform, and the collector and emitter of the second transistor. The supply of power that was supplied to the latch circuit via the second transistor is stopped due to the disconnection between the two, and therefore the heating of the microwave oven is stopped by opening the contact of the relay that opens and closes the energization to the heating device. And the problem that a to-be-heated material continues heating abnormally can be avoided.

Further , the microcomputer is connected to the first output terminal for supplying a rectangular pulse voltage to the pulse smoothing circuit, the second output terminal for controlling conduction of the first transistor, and the operation start switch. The third output terminal, and the latch circuit includes third and fourth transistors, the operation start switch is connected to the fourth transistor, and the third transistor is connected to the third transistor. Power is supplied through the second transistor, and the output terminal of the pulse smoothing circuit is connected to the second transistor, so that the second output terminal is connected when the operation switch is operated. Generate a pulse waveform, supply power to the latch circuit before pressing the operation start switch, and turn on the fourth transistor when the operation start switch is pressed, At the same time, the first transistor is turned on by the signal from the second output terminal, and the relay that opens and closes the power to the load is operated to push the operation start switch until power is supplied to the latch circuit. It is possible to solve problems that must be continued.

The second invention is a capacitor used in a pulse smoothing circuit, in particular, by using a high frequency of 1 kilohertz or more as the frequency of the first output terminal for supplying the rectangular wave pulse voltage of the first invention. Therefore, it is possible to use a ceramic capacitor using a ceramic material that has a low failure rate and little deterioration, and is relatively inexpensive and can improve circuit reliability.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block diagram of a control device according to the first embodiment of the present invention.

  In FIG. 1, the operation unit has an operation start switch for instructing the start of operation, and the microcomputer outputs a rectangular wave pulse voltage from the first output terminal in response to the input of the operation signal, and makes the second transistor conductive. To supply power to the latch circuit. Further, the operation start switch signal of the operation unit makes the latch circuit conductive, and the control of the configuration that operates the relay that energizes the first transistor by energizing the first transistor by the signal from the second output terminal of the microcomputer. It is a device.

  About the control apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, when the user operates the heating start switch of the microwave oven equipped with the control device of the present invention, the microcomputer detects the operation signal and outputs a rectangular wave pulse signal from the first output terminal, and the pulse smoothing circuit Smoothes the rectangular wave and turns on the second transistor to supply power to the latch circuit. At the same time, the operation signal from the operation unit makes the latch circuit conductive. Further, the microcomputer operates a relay that energizes the first transistor by energizing the first transistor by a signal from the second output terminal, thereby operating a conventional logic circuit such as a microwave controlled by a microcomputer. In general, since the relay is driven by the output terminal of the microcomputer, the heating is started by the runaway of only the microcomputer, or the clock circuit of the microcomputer fails as in the above-mentioned conventional patent. However, the control circuit of the present invention does not automatically start heating unless the user operates, and the microcomputer operation stops halfway. Heating of the object to be heated continues even under abnormal conditions such as Without, it is possible to provide a control apparatus adapted to stop safely.

(Embodiment 2)
FIG. 2 is a circuit diagram of a control device according to the second embodiment of the present invention.

  In FIG. 2, an operation unit 1 includes an operation start switch 2 and other operation switches 3, and includes a microcomputer 4, a latch circuit 5, a relay 6 for opening and closing power to a load, the relay 6, and the latch circuit. A transistor Q1 connected between the block 5; a transistor Q2 for supplying power to the latch circuit 5; and a pulse smoothing circuit 7 connected to the transistor Q2. The microcomputer 4 includes an output terminal for a first output terminal 11 for supplying a rectangular wave signal voltage 10 to the pulse smoothing circuit 7, and an output terminal for the transistor Q1. The first latch circuit 5 has a terminal for the second output terminal 12 for controlling conduction and a terminal for the third output terminal 13 connected to the operation unit 1. Transistors Q3 and Q4 having respective collectors connected to respective bases, the operation start switch 2 being connected to the base of Q4, and the power being supplied to the emitter of Q3 via the transistor Q2, The output terminal of the pulse smoothing circuit 7 is connected to the base of Q2, and the microcomputer 4 outputs a rectangular wave signal voltage 10 from the first output terminal 11 when there is a signal from the operation unit 1, and then the operation The control device is configured to drive the relay 6 by outputting an output signal for conducting the transistor Q1 from the first output terminal 12 after the start switch 2 is pressed.

  About the control apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, when the user operates the operation switch 3 in order to use the microwave oven equipped with the control device of the present invention, the microcomputer 4 responds to an input signal from the input terminal 8 of the operation switch with a first output. The rectangular wave signal voltage 10 is output from the terminal 11, and the pulse smoothing circuit 7 smoothes the rectangular wave and supplies current to the base of the transistor Q2, thereby conducting the connection between the collector and the emitter of Q2, and supplying power to the latch circuit 5. To do. The latch circuit 5 includes transistors Q3 and Q4 having respective collectors connected to respective bases, and the operation start switch 2 is connected to the base of Q4. When the operator presses the operation start switch 2, the emitters and collectors of the transistors Q4 and Q3 are brought into conduction. At the same time, the microcomputer 4 receives a signal indicating that the operation start switch has been pressed from the input terminal 9 of the operation start switch, and drives the relay 6 by turning on the transistor Q1 through the second output terminal 12, for example, electronic In the case of the range, heating of the object to be heated is started. Further, in order to know which switch in the operation unit 1 is pressed, the microcomputer 4 is a control device provided with a third output terminal 13.

  As described above, in the present embodiment, in addition to the first embodiment of the present invention, in the case of a microwave oven, for example, when the operation switch 3 is operated by setting the heating time of an object to be heated. If the rectangular wave signal voltage 10 is sent to the pulse smoothing circuit 7 and the power is supplied to the latch circuit 5, the latch circuit operates by simply pressing the operation start switch 3 for a moment to instruct the microwave heating start. can do. On the other hand, if the power is not supplied to the latch circuit 5 through the pulse smoothing circuit 7 in advance, the disadvantage that the operation start switch 2 must be kept pressed until the power is supplied can be solved.

  In addition, the control device of the present invention keeps the magnitude of the base current for controlling the conduction of the transistor Q2 constant between the frequency of the rectangular wave signal 10 and the capacitors C1 and C2 in the pulse smoothing circuit 7. Therefore, the frequency is usually 1 kHz or higher.

  The operation and effect will be described. As a result, the base current for driving the transistor Q2 connected to the pulse smoothing circuit 7 is supplied from the output terminal 11 of the microcomputer 4.

  Since the AC resistance value of the capacitor C1 in the pulse smoothing circuit 7 is R = 1 / (2 * Pai * f * C), if f, that is, the frequency is increased, the resistance value R is decreased, so that the base current is increased. . That is, in order to ensure a constant base current, the capacitor capacitance C can be reduced by increasing the frequency.

  As a result, the capacitors C1 and C2 in the pulse smoothing circuit 7 connected to the first output terminal 11 that supplies the rectangular wave signal voltage 10 can reduce the capacitance of the capacitor as the frequency is increased. Further, a ceramic capacitor using a ceramic material with a low failure rate and little deterioration can be used, and it is relatively inexpensive and can improve the reliability of the circuit.

  As described above, the control device according to the present invention does not automatically start heating unless the operator presses the start switch even when the microcomputer, which has been a conventional problem, runs out of control. Even if the clock circuit attached to the computer stops, it is possible to provide a control device that does not continue to heat the object to be heated. The present invention relates to a control device for a runaway caused by a failure of a logic circuit component in a device controlled by a circuit, and can be applied to a use as a safety device for a machine other than a heating device.

The block diagram of the control apparatus in Embodiment 1 of this invention Circuit diagram of control device in embodiment 2 of the present invention Circuit diagram of conventional control device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Operation part 2 Operation | movement start switch 3 Operation switch 4 Microcomputer 5 Latch circuit 6 Relay 7 Pulse smoothing circuit 8 Input terminal of operation switch 9 Input terminal of operation start switch 10 Rectangular wave signal voltage 11 1st output terminal 12 2nd Output terminal 13 Third output terminal Q1 First transistor Q2 Second transistor Q3 Third transistor Q4 Fourth transistor

Claims (2)

An operation unit, a microcomputer, a latch circuit, a relay for opening and closing power to a load, a first transistor connected between the relay and an output terminal of the latch circuit, and the latch circuit And a second transistor connected between the pulse smoothing circuit and the latch circuit and supplying power to the latch circuit, and the operation unit has an operation start switch for instructing the operation start. The microcomputer has a first output terminal for supplying a pulse voltage of a rectangular wave to the pulse smoothing circuit, and a second output terminal for controlling conduction of the first transistor, and the latch circuit A third transistor and a fourth transistor; the operation start switch is connected to the fourth transistor; and the second transistor is connected to the second transistor. Power is supplied via the Njisuta, said the second transistor control device for a structure in which an output terminal of the pulse smoothing circuit is connected. 2. The control device according to claim 1, wherein an output frequency for supplying a rectangular pulse voltage is 1 kilohertz or more .

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